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pipe length for basement bathroom fan

02-04-2013, 12:46 PM

I have an unused dryer outlet opening. Now I need a basement bathroom fan. It will be nice to use that existing opening. But it is about 25ft away. Piping from bathroom to that opening is easy. Do you think it is a good idea to have a 25ft long passage for the dump air flowing out the basement? insulate the pipe for condensation concern?
thanks

Is this a full bath with tub/shower, steam room or whirlpool tub? If so, you should use solid pipe to avoid the bellies you would get when using flex duct, and pitch it down gently toward your outlet. If it is a half bath - toilet and sink you may use flex duct with no worries. I can't find anything concerning maximum lengths for a horizontal run for a bath exhaust fan although you should take your square footage, say 10 X 10=100 square feet and multiply by 1.07 for a total of 107 square feet and buy the next larger size in cfm capacity. Insulate the pipe if you are exhausting moisture laden air from the bathroom to the outlet.

I have an unused dryer outlet opening. Now I need a basement bathroom fan. It will be nice to use that existing opening. But it is about 25ft away. Piping from bathroom to that opening is easy. Do you think it is a good idea to have a 25ft long passage for the dump air flowing out the basement? insulate the pipe for condensation concern?
thanks